The gender balance is equal for law/medicine mostly at the school level[1].
And with regards to school[2]: "Research finds that men engage in more abstract thinking about many topics—using categories, generalizations—while women are more disposed to context-specific thinking—in terms of concrete situations and relationships. This is evident, for one thing, in how some psychologists contrast the moral reasoning of males and females. Males’ moral judgments tend to be governed by abstract principles of justice, duty, and fairness that apply to all people and situations (e.g., whether a law is broken, whether justice is served). Females’ moral judgments give more weight to specific relationships between people and extenuating circumstances in a given situation; moral judgments are made through subjective feelings (e.g., whether someone feels betrayed or harmed) rather than abstract principles."
And we know from other research, that people who fail in introductory programming classes, fail on that point exactly - they have problems with working with programs that manipulate variables without some meaning.
Add to that that in many fields of study women choose, there's relatively a lot of human interactions, and the goals are towards helping humans,one would see why CS doesn't have the biggest appeal for females ,and why the story of other professions evolved differently.
And that might guide us to some changes in CS curriculum - like maybe teaching in a more concrete way. But one wonders , isn't good CS mostly about abstraction ?
[1]http://onlinelaw.wustl.edu/women-law-infographic/
[2]http://www.scientificamerican.com/article/sex-roles-and-seei...